From: Michal Hocko <mhocko@suse.cz>
To: Li Zefan <lizefan@huawei.com>
Cc: Li Wang <liwang@ubuntukylin.com>, Matthew Wilcox <matthew@wil.cx>,
Cong Wang <xiyou.wangcong@gmail.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Sage Weil <sage@inktank.com>,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
LKML <linux-kernel@vger.kernel.org>,
Yunchuan Wen <yunchuanwen@ubuntukylin.com>
Subject: Re: [PATCH 0/5] VFS: Directory level cache cleaning
Date: Tue, 17 Dec 2013 14:55:06 +0100 [thread overview]
Message-ID: <20131217135506.GD26640@dhcp22.suse.cz> (raw)
In-Reply-To: <52B01594.80001@huawei.com>
On Tue 17-12-13 17:12:52, Li Zefan wrote:
> On 2013/12/17 15:23, Li Wang wrote:
> > If we do wanna equip fadvise() with directory level page cache cleaning,
> > this could be solved by invoking (inode_permission() || capable(CAP_SYS_ADMIN)) before manipulating the page cache of that inode.
> > We think the current extension to 'drop_caches' has a complete back
> > compatibility, the old semantics keep unchanged, and with add-on
> > features to do finer granularity cache cleaning should be also
> > desirable.
> >
>
> I don't think you can extend the drop_caches interface this way. It should
> be used for debuging only.
Completely agreed. The interface shouldn't be further extended. I would
even argue it shouldn't be used in the first place.
> commit 9d0243bca345d5ce25d3f4b74b7facb3a6df1232
> Author: Andrew Morton <akpm@osdl.org>
> Date: Sun Jan 8 01:00:39 2006 -0800
>
> [PATCH] drop-pagecache
>
> Add /proc/sys/vm/drop_caches. When written to, this will cause the kernel to
> discard as much pagecache and/or reclaimable slab objects as it can. THis
> operation requires root permissions.
>
> ...
>
> This is a debugging feature: useful for getting consistent results between
> filesystem benchmarks. We could possibly put it under a config option, but
> it's less than 300 bytes.
>
> Also see http://lkml.org/lkml/2013/7/26/230
>
> --
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--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2013-12-17 13:55 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-16 15:00 [PATCH 0/5] VFS: Directory level cache cleaning Li Wang
2013-12-16 15:00 ` [PATCH 1/5] VFS: Convert drop_caches to accept string Li Wang
2013-12-16 15:00 ` [PATCH 2/5] VFS: Convert sysctl_drop_caches to string Li Wang
2013-12-16 15:00 ` [PATCH 3/5] VFS: Add the declaration of shrink_pagecache_parent Li Wang
2013-12-16 15:00 ` [PATCH 4/5] VFS: Add shrink_pagecache_parent Li Wang
2013-12-16 15:00 ` [PATCH 5/5] VFS: Extend drop_caches sysctl handler to allow directory level cache cleaning Li Wang
2013-12-16 17:45 ` [PATCH 0/5] VFS: Directory " Cong Wang
2013-12-17 3:08 ` Li Wang
2013-12-17 3:58 ` Matthew Wilcox
2013-12-17 7:23 ` Li Wang
2013-12-17 9:12 ` Li Zefan
2013-12-17 9:31 ` Li Wang
2013-12-18 1:26 ` Li Zefan
2013-12-17 13:55 ` Michal Hocko [this message]
2013-12-17 22:05 ` Dave Chinner
2013-12-18 1:36 ` Li Wang
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